FIG. 1 is a view depicting an example of a frequency spectrum of a broadcast wave signal 101 received in a demodulation circuit in a digital television receiver. The broadcast wave signal 101 is an intermediate frequency (IF) signal, for example. When a noise 102 is mixed in the broadcast wave signal 101, the noise 102 becomes a cause of quality deterioration of the broadcast wave signal 101 due to the same frequency (Co-Channel) interference. The noise 102 is, for example, a noise generated from a peripheral device or a noise of the demodulation circuit itself in the digital television receiver, and is a sinusoidal signal of a single frequency.
There has been known an interference wave elimination circuit including: a phase locking means phase locking a signal to a carrier frequency of an interference wave received with a selected received wave; a level adjusting means adjusting a level of the signal phase locked in the phase locking means; and a subtracting means subtracting the signal whose level is adjusted in the level adjusting means from the received wave, in which the received wave from which the received interference wave is eliminated is output from the subtracting means (see, for example, Patent Document 1).
Further, there has been known an OFDM receiving apparatus having highly accurate reception performance even in the case when the same channel disturbance of an analog TV signal or CW disturbance exists (see, for example, Patent Document 2).
[Patent Document 1] Japanese Laid-open Patent Publication No. 2001-339320
[Patent Document 2] Japanese Laid-open Patent Publication No. 2003-283454
In Patent Document 1, in order to eliminate the interference wave, a loop in a phase locked loop (PLL) circuit is used, and thereby a replica of the interference wave is generated from the input signal and the replica is subtracted from the input signal. However, in the above method, when a level of the interference wave is smaller than that of a desired wave, phase comparison in the PLL circuit is not performed, so that it is impossible to obtain a sufficient effect. Further, in the case when an interference wave that arrives with a time lag due to reflection exists (fading), there is sometimes a case that an irregularity occurs in a frequency spectrum to be erroneously detected as a noise, resulting that performance deteriorates.